Are PSA Guarantees Safe?

[Account Closed]

Apologies for the incessant questions but I have another with respect to the deal I'm involved in (fitness center here in California).

The property in question isn't set to be completed until April of next year but the seller wants to close ASAP. We won't get a Certificate of Occupancy until construction is complete which is several months after close of escrow.

PSA states that the seller will guarantee delivery of Certificate of Deposit once construction is complete even though the terms of the LOI stated we would receive the Certificate prior to close.

Question is, is it safe to assume the seller will deliver the Certificate or are there possible/potential complications that can arise that would prohibit them from doing so? Is a "guarantee" in a PSA safe?